It is well known within the art that tap-holes of arc furnaces, blast furnaces or smelter furnaces are exposed to extreme conditions. Molten slag and metal are discharged from such furnaces through one or more tap-holes arranged in the lower section of the arc, blast or smelter furnace. Due to the high temperatures and the aggressive environment, the tap-hole wears out every time metal or slag is discharged. Therefore, each tap-hole can only be used for a limited number of taps before it has to be replaced. In more severe processes, the tap-hole is already worn-out after approximately 100 taps, which corresponds to 2 or 3 weeks of continuous operation.
Currently, tap-holes are refurbished by rebuilding each tap-hole manually with preformed bricks, which are clayed in the worn-out tap-hole of the arc, blast or smelter furnaces to form a “refurbished” tap-hole. Prior to bringing new bricks manually into position, old bricks have to be removed from the surroundings of the hot tap-hole.
As every arc, blast or smelter furnace has to be shut down prior to repairing the tap-holes, it is important that the repair is carried out as fast as possible. Cooling the arc, blast or smelter furnace down will require additional heating up time, which is an additional production and energy loss. Once repaired, the tap-hole needs to stay in working condition for as long as possible. Therefore, it is important that specialized craftsmen carry out the repair. Such craftsmen are difficult to find and their job is quite dangerous, since the old bricks and the casing of the arc, blast or smelter furnace are still very hot (about 500° C.-600° C.) even when the arc, blast or smelter furnace has been shut down. To prevent the craftsmen from being hurt, the procedure of repairing tap-holes has to be carried out very carefully.
As the craftsmen are working in a hazardous area, the preformed bricks for refurbishing the tap-holes are often not well positioned. In consequence, the discharged metal or molten slag can get between the bricks, wash out the filling and dislodge them. Therefore tap-holes, which are refurbished with preformed bricks, are not performing uniformly and may need to be replaced more frequently.
GB2 203 526 describes a method to refurbish a plug fitted in the sidewall of a steel-making vessel where the refractory material sealing the plug in place has been burned off after a number of pourings to create an enlarged approach well inside the steel-making vessel. A steel pipe is placed from the inside of the vessel in the worn plug using a boom and the steel pipe is sealed in place by a refractory material and the well is filled with settable refractory material which sinters or fuses with heat to effect the repair.
EP 0 726 439 describes a method of repairing a metallurgical vessel in the region of its tapping pipe, where a tapping pipe is inserted from below into the brickwork and held in place and then the gap between the pipe and the brickwork is filled from below with a filling material. Also disclosed is an arrangement for carrying out the method with a pressure plate on which the pipe can be placed, with diameter greater than the outside diameter of the gap. The pressure plate has an aperture through which the filling material can be inserted.
JP2004218022 describes a method for repairing a blast furnace tap-hole, comprising the steps of inserting a large block made of refractory for repairing the tap-hole. The block is a preformed two-layered structure which is set in position by press fitting the irregularly shaped refractory bricks into the region of the large block for repairing.
KR-100 832 528 B describes a method of re-enforcement of a tapping old sleeve of a converter with a device comprising a tube, a cylinder body and a piston. The tube comprises one or more holes at one end. The tube comprises a connection plate at the opposite end for fixing the tube to the sleeve. The cylinder body includes on one end a connection plate adapted to be mounted on the connection plate of the tube and on an opposite end a gas connection. The method of re-enforcement of the sleeve includes filling the tube with repair material, installing the piston in the tube, and mounting the cylinder body on the sleeve, the rear part of the piston playing the role of a guide of the piston inside the cylinder body. The device is then mounted onto the sleeve. The sleeve is then oriented vertically so that the tube also extends vertically. The gas connection is then pressurized in order to displace the piston upwards and push the repair material through the holes at the other end of the tube. The repair material pours from the holes and flows along the tube in order to fill the gap between the outside surface of the tube and the inside surface of the sleeve. After the repair material has dried, the device is dismantled and the tube is removed from the tapping hole.